Numerous body restraint systems have been used in manned space missions. Not all of them are full body restraint systems in that they restrain the user only at one body point. Devices used by NASA on the Skylab missions included foot loops on the floor, a triangle shoe and grid system, a wardroom table thigh restraint, and an ATM chair restraint. The Soviet cosmonauts have used body restraints designed mainly around elastic cords which harness the user.
A variety of restraint systems not intended for zero or microgravity use are also known in the art. For example, U.S. Pat. No. 2,976,914, issued Mar. 28, 1961 to Miller, discloses Velcro fasteners for floor cushions in an aircraft cabin. U.S. Pat. No. 3,165,168, issued Jan. 12, 1965 to Rose, discloses a boatswain's chair waist restraint. U.S. Pat. No. 4,235,182, issued Nov. 25, 1980 to Burger, discloses a chest, foot and hand restraint system for water skiing and windsurfing. U.S. Pat. No. 4,457,510, issued July 3, 1984 to Pertschuk, discloses the use of Velcro pads to hold the user's feet against a wall while exercising. U.S. Pat. No. 4,591,148, issued May 27, 1986 to Slater, discloses the use of Velcro pads with a clamp to hold the user's feet against a door while exercising. U.S. Pat. NO. 4,637,629, issued Jan. 20, 1987 to Cummings, discloses a flexible torso restraint for aircraft crew members that allows body movement within a localized space.
In general, past approaches for zero gravity body restraints have been ineffective in part or in whole due to (1) the position into which they put the user's body and, as a result, the strain required to use the device and (2) the level of complexity involved in the use of the device. The foot loops used on Skylab required that the user constantly strain his or her toes against the loops in order to be restrained. The triangle shoes and grid arrangement put the user in a flat-footed position, which made the user strain against the dropped foot position assumed in the neutral body position in zero gravity. The system required the user to be precise in foot placement, and it was necessary to unlock oneself from the grid to be released, both of which were difficult to do quickly. Other problems were the massiveness of the cleat and the requirement to bend over to lace the high top shoes used, a difficult task in zero gravity. The thigh restraints produced another body position problem. Since these restraints straightened the user out, in order to use the wardroom table, it was necessary effectively to go into a sit up position and hold it. The chair restraint system proved altogether unacceptable as there is no need to try to sit in zero gravity, and it requires strain by the user to maintain the position the restraint induces.